There are a multitude of benefits to aquaponic farming compared to the traditional farming operations used by most farmers. For the most part, aquaponic farming produces healthier crops quicker than traditional farming operations.
Using drip irrigation with aquaponics can also give you more control over where the water goes, wasting little water, which helps with water bills.
Another important component of aquaponics is being a growth medium instead of soil.
Thus, that means the crops grown this way are naturally more resistant to soil-borne infective and weeds.
Shortcomings of Aquaponics
Even though growth mediums have significant advantages, they also have their disadvantages.
First off, no matter how good they are, they are never going to substitute for soil.
That is because they are only supportive of the plant you are growing – there’s no nutrient content in it to help the plant grow and actively develop. They also require a considerable upfront investment.
So, for your plants to be healthy and happy using growth mediums:
- You will have to choose the porous option to help with aeration and water for circulation effectively.
- Then you can spend a little time to get the nutrient solution that contains all the minerals necessary for plants growth.
So, how do you select the ideal growing medium for your drip system?
Continue reading for some useful advice, so that you can provide a well-informed choice!
Before choosing the best growing medium for a drip system, it is wise to understand the following traits/characteristics:
- Air Filled Porosity
- Cation Exchange Capacity
- Water Holding Capacity
Air Filled Porosity
Air filled porosity, is a term used to define how the air is moving through your chosen growth medium.
When air filled porosity is low, it also indicates low aeration quality.
If there is low air filled porosity, it is also an indicator as to whether or not the crops are receiving the necessary oxygen to promote a healthy plant and maintain metabolism levels. If not, it cause the crops to not develop as they typically would.
Therefore, plants will mature slower than they would with a more favorable air filled porosity, and with extremely low air filled porosity, crops can die, drown or rot.
Cation Exchange Capacity
Cation Exchange Capacity (CEC), means that medium’s ability to hold onto positively charged ions (cations) like calcium, magnesium, and potassium.
When talking about total air filled porosity, for some situations, it would actually better for a growth medium to have low cation exchange capacity.
That’s because this makes it easier to control the types of minerals your crops get.
On the flip side, if you’re using a medium with a high cation exchange capacity, it can create complications to hold the right balance of nutrition.
Just think… you might be hiring an entire pro to formulate a custom solution with the balance of nutrients you want your plants to receive.
Water Holding Capacity
Water holding capacity refers to how well a substrate can hold water.
It’s good to have an idea of what the medium’s capacity is, because some substrates perform better when they hold less water, while others perform well when they hold more.
If you are unsure what the appropriate capacity is for your substrate, it is best to consult a professional.
Common Types of Growth Mediums
Now that we have addressed the most important aspects to consider when purchasing a growth medium, let’s look at some of the more commonplace growth media you will find on the market:
- Coconut Fiber, also known as Coconut Coir
- Lightweight Expanded Clay Aggregates
- Perlite
- Rockwool
Coconut Fiber (Coconut Coir)
The outside husk of coconuts – specifically, the coconut coir growing medium – is the third natural option for growing media along with peat and compost.
Along with fibers, coconut coir can also be found in chips and pith (fine powder). Coco coir, as a growing medium has been shown to be more soil-like than peat and compost.
Coconut coir is most closely similar to soil when comparing the properties of the two growing mediums:
- It can sift nutrients to prevent your plants from experiencing the consequences of consuming too much or too little of something.
- In addition, coconut fiber is excellent for retaining water which means you can go longer between waterings.
You can afford to skip watering your crops for a day or two.
Moreover, coconut fiber has a neutral pH and perfect oxygen to water ratio.
These features along with its ability to sustain high water retention capacity are delightful for how much time a person can afford to devote to watering their crop.
From experience, Purchase a coco coir growing medium that has been buffed and rinsed properly.
Lightweight Expanded Clay Aggregates
Lightweight Expanded Clay Aggregate is produced by heating clay pellets.
Typical aggregates have high air-filled porosity, so there is a sufficient supply of oxygen.
Aggregates also have low cation exchange capacity and low water holding capacity.
Due to the low water holding capacity of the clay pebbles, they allow for air circulation without damaging the moisture level in your growth medium;
However, it’s a double-edged sword.
If you have a pump failure and the plants are not receiving enough water, they will probably wilt.
It is very important to routinely monitor your irrigation system, with clay pebbles or similar aggregates, to limit complications associated with under-watering.
Perlite
When mixed with other growth mediums, Perlite is unique from other growth mediums.
Perlite is lightweight, has a high air-filled porosity, and low cation exchange capacity.
This allows better management of nutrient uptake in your crops.
However:
- Because Perlite retains so much moisture, most growers will apply too much water when using it.
- It also floats in water, so it’s not ideal for use with any plant species that like the moisture.
Rockwool
Gardeners frequently turn to Rockwool as a growth medium because it is easy to obtain and easy to use.
Rockwool as a medium is sold in blocks, retains water well, and has a very low cation exchange capacity.
The main downside, which is why some farmers try to stay away from this material, is that it is not biodegradable.
Smart Move: You also want to soak the blocks in water before use to get the pH lowered so you do not contribute to harm to your plants.
Final Words
The caliber of your production is directly connected to your inputs for growing your products.
One way of making good decisions in your growing processes, is making the best decisions on what growth medium to use.
If you lack confidence with your knowledge, reach out to your professional contact, or ask someone trusted in your life.
And again, take your time with that decision; there is absolutely no sense in going with one way of thinking and regretting your choice after!